Reflow solder convection ovens are typically used in the production of printed circuit boards employing surface mount technology. Most convection ovens include a number of heating zones spaced along a conveyer which carries the printed circuit boards through the various heating zones. Each heating zone usually includes upper and lower heating elements, and a blower or fan associated with each heater element. The fan blows air or some other gas such as nitrogen through the heater element, and the heater element heats the gas before it moves over and about the printed circuit board.
In prior art systems, the currently available fans fail to provide uniform flow across the span of a given heater element. For example, the gas flow velocity on one edge of the heater element could be 20% less than on the opposite edge or at the location where the fan mounts to the heater element. And, the gas temperature also varies by as much as 20% across the heater element. These variations result in imprecise temperature controls and variable heating of the printed circuit boards which can adversely affect quality. Adding additional fans can be expensive and is not always possible due to space limitations.